From patchwork Thu Nov 17 16:24:16 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kumar Kartikeya Dwivedi X-Patchwork-Id: 13047016 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7D8C1C4167D for ; Thu, 17 Nov 2022 16:26:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240471AbiKQQ0p (ORCPT ); Thu, 17 Nov 2022 11:26:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35328 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239727AbiKQQ0Z (ORCPT ); Thu, 17 Nov 2022 11:26:25 -0500 Received: from mail-pg1-x542.google.com (mail-pg1-x542.google.com [IPv6:2607:f8b0:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3075D7C443 for ; Thu, 17 Nov 2022 08:25:13 -0800 (PST) Received: by mail-pg1-x542.google.com with SMTP id 136so2437351pga.1 for ; Thu, 17 Nov 2022 08:25:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=DbEyJK9HHakkaLmZTBG+aVA2e5HoR3xLLcJ7jqCnp4M=; b=BKbSKqrdmLVrtc64a+MtBTSK+aQGFSpcwtnZf352X9YS1dx49v8ZcZwivO5RDa4vZj 7+yqpeYBlivSNdxzKYQ2u5+By974GaIntly4+C5R1eZ4SBiW785fGkdTzOXVmyrPwJTc /c0GtkpbmwMqz9y2y+eIj85whrJk5qHMVi5OvBbWb6MXnkc+5SG4Yx4tO5d8omthTTII 9LDVlwtrH88ooORe/d1sKBmdh0/Ze4ra4FH4JNyvSuq4V5OpXd+zEAA3nQeJLhJTVWu3 jCo81Gbnx56hyq7K+NOHGyzVkUpyrX7YE4lUIrOCRv5Y9fTdYdNeMCMAZ/wT2BuKlPvY Cypw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=DbEyJK9HHakkaLmZTBG+aVA2e5HoR3xLLcJ7jqCnp4M=; b=qIfnsTBwiWr+hQNQrA3G6xRJERpwEhFv+wV5RZaBN6dRrEjRpNm9o77rl7wHYcnyMT Sxl5KDa8dSAxYTMek+7LIz/ari00+bYVp5VJsgEaTEtFavPMlQRw4uiBc1zqWa8gaETA 5JJblGjuNWbUB9G3l7E8gKLG+n2TZG/rzRh1lQTk0M9NpjLRW0ZNGfx1VHq9TC/Sk/+N moNpa9dEeoamN9t+vqAdagy8pHfoZMkRjN5rKNQlojY/Dx0CYsnEn02qnml9CPpUDmgN fqU45blQJQrJP7L8A4Rx/18v6Hl6fIyGSFMpLA+BaWR2wcOEbnvICCdeEeIpbzyoTlqh PF5A== X-Gm-Message-State: ANoB5plfmwmhLln7XZtbNh8Aq7F8nVXTWnTOWHa55JO1jv4Zt4AXs5dK ViT9TOFK8unUVMuCbZMR0aIcViMrnvg= X-Google-Smtp-Source: AA0mqf6OKEmoumm+PXwWq1kSiI3D+xLZ8US16dS9YnpmwAnNO+oFHxJ81NuxMAHyeAIYuItK1Kr5Lg== X-Received: by 2002:aa7:84c5:0:b0:56b:f64b:b385 with SMTP id x5-20020aa784c5000000b0056bf64bb385mr3592547pfn.68.1668702312135; Thu, 17 Nov 2022 08:25:12 -0800 (PST) Received: from localhost ([103.4.221.252]) by smtp.gmail.com with ESMTPSA id h129-20020a625387000000b0056c063dd4cfsm1367554pfb.66.2022.11.17.08.25.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Nov 2022 08:25:11 -0800 (PST) From: Kumar Kartikeya Dwivedi To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Martin KaFai Lau , Dave Marchevsky Subject: [PATCH bpf-next v8 08/22] bpf: Allow locking bpf_spin_lock in allocated objects Date: Thu, 17 Nov 2022 21:54:16 +0530 Message-Id: <20221117162430.1213770-9-memxor@gmail.com> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221117162430.1213770-1-memxor@gmail.com> References: <20221117162430.1213770-1-memxor@gmail.com> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=8926; i=memxor@gmail.com; h=from:subject; bh=ae8q9s9cDVzghCLBYYIt/0OQIWliZosyXk12KKyNFuE=; b=owEBbQKS/ZANAwAIAUzgyIZIvxHKAcsmYgBjdl7/tufLpx78Y1jeLtm63SLV+2UVK0aVakc7X0u1 XlbMtHmJAjMEAAEIAB0WIQRLvip+Buz51YI8YRFM4MiGSL8RygUCY3Ze/wAKCRBM4MiGSL8Ryu19EA CH8CfQQYpmYDtodR9+sBi9NHKPjdXJ8073LmaL3HztR/zdfsQ7vrA2BzeKBM5yNze87UTk6Z11eVs9 YHl8n99BnodU7ViXCDkUPkGQmdQD80RXjx5YOMZ92XULnDQMI6bDQFHXtdy9yoB/GArgO2y3tn9cTe DhOdUc7A3Ou6Kn2t2oJym0xnpWF8IIDp+Hf3xvHCmEhlyriItPKLm7mzWFKqUPk29dajK+Vwt40W/4 SA5gqxCKX+uooNJMS89igMZRDi/hQepx/KueOGkWM7JYlAXbkRL2cHWCgFIOwig4j9GzTfRlLPsPMk A8wPneEsibsjAHlL4/EubBlTh6pZOvXEeHN01JoMjrctzP3S1qF+4XFBhvopUyyCkYp8Xro9XU5EOG 9uczszlSFwwMV5oxFGdML2SM1II1tlH2tJ7JNXgIaFzn+v0nJBGVM0WgnPYIv+xXVISIOUDahABJ1t CmGaam0PVJLM2Mmy1xRdBB8fGO1k61PG0zpVdQ95HS96VpkCbFdIpRkJN3YvoVBLYwFbi26egAAGHI tlHjETZFGbNGCRDZ2uGL8srPaMEKAbzgO3ECATH5eAVwRhPUA//Og96V0xOvcOwm8DHgZyhu3gRWLm c1a/9qykrlsQgZTdNZGYwHYJRd54Z2IDDX+K/cGOqXd/0sYuEiJxKOioUsQw== X-Developer-Key: i=memxor@gmail.com; a=openpgp; fpr=4BBE2A7E06ECF9D5823C61114CE0C88648BF11CA Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Allow locking a bpf_spin_lock in an allocated object, in addition to already supported map value pointers. The handling is similar to that of map values, by just preserving the reg->id of PTR_TO_BTF_ID | MEM_ALLOC as well, and adjusting process_spin_lock to work with them and remember the id in verifier state. Refactor the existing process_spin_lock to work with PTR_TO_BTF_ID | MEM_ALLOC in addition to PTR_TO_MAP_VALUE. We need to update the reg_may_point_to_spin_lock which is used in mark_ptr_or_null_reg to preserve reg->id, that will be used in env->cur_state->active_spin_lock to remember the currently held spin lock. Also update the comment describing bpf_spin_lock implementation details to also talk about PTR_TO_BTF_ID | MEM_ALLOC type. Signed-off-by: Kumar Kartikeya Dwivedi --- kernel/bpf/helpers.c | 2 + kernel/bpf/verifier.c | 89 +++++++++++++++++++++++++++++++------------ 2 files changed, 66 insertions(+), 25 deletions(-) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 7bc71995f17c..5bc0b9f0f306 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -336,6 +336,7 @@ const struct bpf_func_proto bpf_spin_lock_proto = { .gpl_only = false, .ret_type = RET_VOID, .arg1_type = ARG_PTR_TO_SPIN_LOCK, + .arg1_btf_id = BPF_PTR_POISON, }; static inline void __bpf_spin_unlock_irqrestore(struct bpf_spin_lock *lock) @@ -358,6 +359,7 @@ const struct bpf_func_proto bpf_spin_unlock_proto = { .gpl_only = false, .ret_type = RET_VOID, .arg1_type = ARG_PTR_TO_SPIN_LOCK, + .arg1_btf_id = BPF_PTR_POISON, }; void copy_map_value_locked(struct bpf_map *map, void *dst, void *src, diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 49e08c1c2c61..8eddecfc3a5e 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -453,8 +453,16 @@ static bool reg_type_not_null(enum bpf_reg_type type) static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg) { - return reg->type == PTR_TO_MAP_VALUE && - btf_record_has_field(reg->map_ptr->record, BPF_SPIN_LOCK); + struct btf_record *rec = NULL; + + if (reg->type == PTR_TO_MAP_VALUE) { + rec = reg->map_ptr->record; + } else if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC)) { + struct btf_struct_meta *meta = btf_find_struct_meta(reg->btf, reg->btf_id); + if (meta) + rec = meta->record; + } + return btf_record_has_field(rec, BPF_SPIN_LOCK); } static bool type_is_rdonly_mem(u32 type) @@ -5564,23 +5572,26 @@ int check_kfunc_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state } /* Implementation details: - * bpf_map_lookup returns PTR_TO_MAP_VALUE_OR_NULL + * bpf_map_lookup returns PTR_TO_MAP_VALUE_OR_NULL. + * bpf_obj_new returns PTR_TO_BTF_ID | MEM_ALLOC | PTR_MAYBE_NULL. * Two bpf_map_lookups (even with the same key) will have different reg->id. - * For traditional PTR_TO_MAP_VALUE the verifier clears reg->id after - * value_or_null->value transition, since the verifier only cares about - * the range of access to valid map value pointer and doesn't care about actual - * address of the map element. + * Two separate bpf_obj_new will also have different reg->id. + * For traditional PTR_TO_MAP_VALUE or PTR_TO_BTF_ID | MEM_ALLOC, the verifier + * clears reg->id after value_or_null->value transition, since the verifier only + * cares about the range of access to valid map value pointer and doesn't care + * about actual address of the map element. * For maps with 'struct bpf_spin_lock' inside map value the verifier keeps * reg->id > 0 after value_or_null->value transition. By doing so * two bpf_map_lookups will be considered two different pointers that - * point to different bpf_spin_locks. + * point to different bpf_spin_locks. Likewise for pointers to allocated objects + * returned from bpf_obj_new. * The verifier allows taking only one bpf_spin_lock at a time to avoid * dead-locks. * Since only one bpf_spin_lock is allowed the checks are simpler than * reg_is_refcounted() logic. The verifier needs to remember only * one spin_lock instead of array of acquired_refs. - * cur_state->active_spin_lock remembers which map value element got locked - * and clears it after bpf_spin_unlock. + * cur_state->active_spin_lock remembers which map value element or allocated + * object got locked and clears it after bpf_spin_unlock. */ static int process_spin_lock(struct bpf_verifier_env *env, int regno, bool is_lock) @@ -5588,8 +5599,10 @@ static int process_spin_lock(struct bpf_verifier_env *env, int regno, struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; struct bpf_verifier_state *cur = env->cur_state; bool is_const = tnum_is_const(reg->var_off); - struct bpf_map *map = reg->map_ptr; + struct btf_record *rec = NULL; u64 val = reg->var_off.value; + struct bpf_map *map = NULL; + struct btf *btf = NULL; if (!is_const) { verbose(env, @@ -5597,19 +5610,32 @@ static int process_spin_lock(struct bpf_verifier_env *env, int regno, regno); return -EINVAL; } - if (!map->btf) { - verbose(env, - "map '%s' has to have BTF in order to use bpf_spin_lock\n", - map->name); - return -EINVAL; + if (reg->type == PTR_TO_MAP_VALUE) { + map = reg->map_ptr; + if (!map->btf) { + verbose(env, + "map '%s' has to have BTF in order to use bpf_spin_lock\n", + map->name); + return -EINVAL; + } + rec = map->record; + } else { + struct btf_struct_meta *meta; + + btf = reg->btf; + meta = btf_find_struct_meta(reg->btf, reg->btf_id); + if (meta) + rec = meta->record; } - if (!btf_record_has_field(map->record, BPF_SPIN_LOCK)) { - verbose(env, "map '%s' has no valid bpf_spin_lock\n", map->name); + + if (!btf_record_has_field(rec, BPF_SPIN_LOCK)) { + verbose(env, "%s '%s' has no valid bpf_spin_lock\n", map ? "map" : "local", + map ? map->name : "kptr"); return -EINVAL; } - if (map->record->spin_lock_off != val + reg->off) { + if (rec->spin_lock_off != val + reg->off) { verbose(env, "off %lld doesn't point to 'struct bpf_spin_lock' that is at %d\n", - val + reg->off, map->record->spin_lock_off); + val + reg->off, rec->spin_lock_off); return -EINVAL; } if (is_lock) { @@ -5815,13 +5841,19 @@ static const struct bpf_reg_types int_ptr_types = { }, }; +static const struct bpf_reg_types spin_lock_types = { + .types = { + PTR_TO_MAP_VALUE, + PTR_TO_BTF_ID | MEM_ALLOC, + } +}; + static const struct bpf_reg_types fullsock_types = { .types = { PTR_TO_SOCKET } }; static const struct bpf_reg_types scalar_types = { .types = { SCALAR_VALUE } }; static const struct bpf_reg_types context_types = { .types = { PTR_TO_CTX } }; static const struct bpf_reg_types ringbuf_mem_types = { .types = { PTR_TO_MEM | MEM_RINGBUF } }; static const struct bpf_reg_types const_map_ptr_types = { .types = { CONST_PTR_TO_MAP } }; static const struct bpf_reg_types btf_ptr_types = { .types = { PTR_TO_BTF_ID } }; -static const struct bpf_reg_types spin_lock_types = { .types = { PTR_TO_MAP_VALUE } }; static const struct bpf_reg_types percpu_btf_ptr_types = { .types = { PTR_TO_BTF_ID | MEM_PERCPU } }; static const struct bpf_reg_types func_ptr_types = { .types = { PTR_TO_FUNC } }; static const struct bpf_reg_types stack_ptr_types = { .types = { PTR_TO_STACK } }; @@ -5946,6 +5978,11 @@ static int check_reg_type(struct bpf_verifier_env *env, u32 regno, return -EACCES; } } + } else if (type_is_alloc(reg->type)) { + if (meta->func_id != BPF_FUNC_spin_lock && meta->func_id != BPF_FUNC_spin_unlock) { + verbose(env, "verifier internal error: unimplemented handling of MEM_ALLOC\n"); + return -EFAULT; + } } return 0; @@ -6062,7 +6099,8 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, goto skip_type_check; /* arg_btf_id and arg_size are in a union. */ - if (base_type(arg_type) == ARG_PTR_TO_BTF_ID) + if (base_type(arg_type) == ARG_PTR_TO_BTF_ID || + base_type(arg_type) == ARG_PTR_TO_SPIN_LOCK) arg_btf_id = fn->arg_btf_id[arg]; err = check_reg_type(env, regno, arg_type, arg_btf_id, meta); @@ -6680,9 +6718,10 @@ static bool check_btf_id_ok(const struct bpf_func_proto *fn) int i; for (i = 0; i < ARRAY_SIZE(fn->arg_type); i++) { - if (base_type(fn->arg_type[i]) == ARG_PTR_TO_BTF_ID && !fn->arg_btf_id[i]) - return false; - + if (base_type(fn->arg_type[i]) == ARG_PTR_TO_BTF_ID) + return !!fn->arg_btf_id[i]; + if (base_type(fn->arg_type[i]) == ARG_PTR_TO_SPIN_LOCK) + return fn->arg_btf_id[i] == BPF_PTR_POISON; if (base_type(fn->arg_type[i]) != ARG_PTR_TO_BTF_ID && fn->arg_btf_id[i] && /* arg_btf_id and arg_size are in a union. */ (base_type(fn->arg_type[i]) != ARG_PTR_TO_MEM ||